1. Field of the Invention
This invention relates to a leukocyte detector, and more particularly to a device for detecting the leukocytes or white blood cells from a microscopic image of a stained blood smear.
2. Description of the Prior Art
Generally, the leukocyte count in the blood is far smaller than the erythrocyte count (the former is approximately 1/1000 of the latter), so that when one observes a hemogram under a microscope, he finds that most of the visual field is occupied by the erythrocytes. Thus, much time is usually taken for detecting the leukocytes when one tries to microscopically examine the leukocytes in a blood smear or to sort out the leukocytes automatically.
There is known in the art an automatic leukocyte sorting apparatus of the following system. In order to detect the leukocytes, first a part of the blood smear is scanned by a flying spot scanner to extract the blue color component and green color component from the transmitted light and these components are converted into corresponding electrical signals, which are then subjected to subtraction by a subtractor and the obtained differential signal is quantized and then guided to a leukocyte detector. A mask is set in this leukocyte detector, and if the pattern formed by said quantized signal is large enough to fill up said mask, it is determined that the leukocytes are present in that portion of the blood smear which was scanned. If no leukocyte is detected, the blood smear is moved by a stepping motor and similar scanning is performed over another portion of the smear.
Such a known leukocyte detecting system, however, has the drawbacks that the construction of the system is extremely complicated and much time is required for detecting the leukocytes as a time-consuming scanning means is used.